A known baler comprises two baling chambers disposed one behind the other. In operation, a first bale is made ready in the rear chamber and deposited on the field, while at the same time a second bale is being formed in the front chamber. After the second bale has been wound to some extent in the front chamber, it is displaced from the front chamber into the rear chamber where, after the first bale has left the rear chamber winding is completed. In this way it was attempted to avoid the necessity of stopping the baler on the field to bind the bale with twine or wire, such binding operation being time-consuming. However the use of two chambers in such a baler has the disadvantage that part of the time available for the formation of a bale is required for displacing a partially complete bale from the front chamber into the rear chamber. This displacement also requires separate means which raises the costs of the baler without directly contributing to the formation or the binding of bales.